For Crohn’s disease patients, dose escalation for insufficient infliximab trough levels led to a marked increase in remission compared to before dose escalation (88% vs 65%).
Furthermore, dose reduction in both diseases—Crohn’s disease and ulcerative colitis—achieved significant cost savings, with no increase in flares or inflammatory markers.
However, the authors reported, 66% in the clinical dosing group and 69% in the trough-level dosing group achieved the primary endpoint, remission—a difference that was not statistically significant.
Still, the authors write: “Our results indicate that adaptive dosing of infliximab based on exposure results in better short-term clinical outcomes and that by maintaining this adequate exposure, the risk for level of response can be reduced.”
In a Gastroenterology editorial, Dr. Shomron Ben-Horin from Tel-Aviv University in Tel Hashomer, Israel calls the lead-in dose optimization phase “a landmark step forward in therapeutic drug monitoring-based care.”
It shows, he continued, that one-time measurement of drug/antidrug antibody levels “during seemingly successful maintenance treatment reveals a non-negligible portion of Crohn’s disease patients who will benefit from dose escalation to achieve better control of underlying inflammation.”
He also gives high marks to the therapeutic dose monitoring strategy in helping patients avoid disease flares and go about their lives normally.
Ultimately, Dr. Ben-Horin predicts, the therapeutic dose monitoring approach will likely guide more optimal induction protocols, as well as proactive dose titration, and finally guide reactive interventions for loss of response to anti-TNF therapies.
Dr. Hanauer, however, notes that as encouraging as the data are, they’re from one center in Europe.
“In Europe, the cost of the assay is about $50, whereas in the United States, the cost ranges between $350 and $2500,” he said. “There are potential cost savings, but more likely, cost increases, based on current cost/dose instead of cost per patient. The cost of the anti-TNFs have been based on rheumatology and dermatology, while the dosing for inflammatory bowel disease is up to two to four times the dosing of rheumatoid arthritis.”
That aside, Dr. Hanauer predicts use of therapeutic drug monitoring will grow. “Therapeutic drug monitoring is being incorporated into treat to target therapies and personalized medicine,” he said.
